1. Field of the Invention
The present invention generally relates to a structure of an electrical contact. More particularly, the invention relates to an electrical contact connecting semiconductor devices and a fabricating method thereof.
2. Description of the Prior Art
As semiconductor processes advance to very deep sub-micron geometries, such as 20-nm node and beyond, and with the progress of device miniaturization, junction resistance between semiconductors and external contact metals has become a critical issue; therefore, there is a strong need to invent electrical contact structures with relatively low junction resistance, which can be used to connecting semiconductors and conductive lines.
In a convention method of fabricating an electrical contact, in order to reduce junction resistance, a self-aligned silicide (salicide) process is utilized to form a metal silicide layer on the junction of metal and semiconductor layer. For example, a semiconductor device covered with a metal layer is provided first. Next, an annealing process is carried out to diffuse atoms inside the metal layer into certain regions, like silicon regions contacted with the metal layer, so that metal silicide layers is formed on the surface of the certain regions. Then, remaining metal layers are removed and another annealing process is performed. During this process, the resistivity of the metal silicide layers can be reduced. An insulation layer, which has a plurality of contact holes, is than formed on the semiconductor device so that the metal silicide layers can be exposed from the contact holes. Finally, a barrier layer and a conductive layer are deposited inside the contact holes to thereby complete a contact structure. The above-saying procedures, however, need at least two annealing processes and a removing process of the metal layer. Such complicated steps are no doubt increase cost of the manufacture and the thermal budget of the semiconductor device is over consumed.
Regarding the drawbacks described above, there is always a continuing need to develop an electrical contact and a fabricating method thereof, which can simply a fabricating process and save thermal budget of semiconductor devices from over consuming.